A blacklist and IP-address database, formerly privately owned but now part of the email vendor Ironport. Many ISPs check the IP addresses of incoming email against Spamcop’s records to determine whether the address has been blacklisted due to spam complaints.

3 Quick And Easy Ways To Build A Profitable Opt-In List
You finally realize that you need a good opt-in list. After reading countless articles and sought expert advices and have read many success stories of people creating a small fortune with opt-in lists you finally decide to have one of your own.